Alloy steel



Patented July 27, 1926.

UNITED STATES ROY T. WIRTH, OF EAST CLEVELAND, OHIO.

ALLOY STEEL.

No Drawing.

The present invention relates to an improved metal alloy which is particularly adapted for use in the manufacture of high speed cutting tools and implements, although it may also be used for various other purposes. The present composition is one which may be varied within quite large.

limits, but which within these limits, furnishes a metal alloy of extreme hardness, and yet an alloy which may be readily formed into various cutting tools.

In my co-pending United States application, Serial No. 443,255, I have described an improved alloy high speed steel which.

makes use of a high chromium content, together with tungsten or molybdenum and iron, and also containing the usual minor ingredients. In the present alloy, I have found that by changing the composition, it

is possible to obtain steel alloys of extreme hardness which are capable of much greater speeds than my previous alloy, and which are in fact as hard and successful in cutting hard substances as alloys such as stellite and the like, which are not steel alloys.

'1 he following description sets forth in detail proved combinations of ingredients embodying my invention, such disclosed combinations constituting several of the various forms in which the principle of the invention may be used.

The present invention relates to steel alloys in which iron is alloyed with chromium and carbon, and also preferably with one or more of the other metals of the chromium group, such as tungsten or molybdenum or both, and it has been found that when these elements are alloyed in correct proportions and within certain limits, that a set of extremely hard alloys is obtained.

These alloys may be composed of iron, chromium and carbon; iron, chromium, carbon and tungsten; iron, chromium, carbon and molybdenum; or iron, chromium, carbon and a combination of tungsten and molybdenum. Uranium may also be used in these compositions, it being a member of the chromium group, but it is usually only used in relatively small percentages because of its higher cost, relative to tungsten and molybdenum. In alloying these metals, it has been found that where molybdenum is employed in place of tungsten, that a lesser percentage of molybdenum is required than the tungsten percentage which it replaces, and that where molydenum is used, the

Application filed October 19, 1921. Serial No. 508,820.

chromium content should be slightly increased to obtain maximum results. It has also been found best to use a rather high carbon content and the following formulas given below, have been found to give satisfactory alloys.

' Chromium; Tungsten. Carbon.

5. 50 58. 00 1. 25. 18.00 42. 50 0. 70 10. 50 55. 00 0.60. 6. 75 47. 50 2. 32. 16.00 28.50 2. so. I 22. O0 25. 00 Low, to silicon. 22. 00 25.00 Low, 3.25 boron.

Chromium. Molybdenum. Carbon.

25.00 10.00 1.00 (A 26. 00 lggffuue 2.00 (B).

1 ungs en I 5 {22.33 znolygdenumml 90 (A 1. ungs en I 24'00 3.50 molybdenum-.. l (B Chromium. Carbon. Iron.

31 1.25 Balance. 48. 00 1.80 Do. 45.00 1.25 Do.

It will be seen from the foregoing formulas, that the total chromium and tungsten content 40 per cent in any one of the alloys mentioned, and it is as high as about 65 per cent in some of the allo s. It will also be noticed that where the c romium content 15 low that the tungsten content is relatively very high. In each case where the chromium content is below 10 per cent, the tungsten content is above per cent, and where the chromium content is relatively hlgh, the tungsten content is lowered, but at no time is the tungsten content less than 15 per cent nor has it been found feasible to use a chromium content greater than 30. per cent.

Where the alloy contains merely iron, chromium and carbon, without tungsten and molybdenum, the chromium content ranges from 30 to per cent, thus approximatlng the total content of chromium and tungsten where both of these metals are used. Where the chromium content is small, the carbon content is usually increased somewhat and may run as high as three per cent.

In the formulas it will be noticed that two formulas are marked A and B and the formulas which contain molybdenum or molybdenum and tungsten which correspond in results with the. formulas A and B are marked-A and A, and B. and B and the lesser-amounts of molybdenum and tungsten show approximately the difference between the amounts of these. metals which mustbe used in order to obtain approxi-- mately the same results.

In general, the foregoing formulas show that iron may be alloyed with chromium and carbon, and also with one or more of the other metals of the chromium group to metals of the chromium group are employed,

the total used is not less than 35 per cent and may run up to approximately 7 0 per cent.

' Some alloysthus have a very high chromium content and all have a very high total con-;

tent of the metals of the'chromium group.

It is of course to be understood that small quantities of other; metals or non-metallic elements may also be employed to obtain special results, and thus the following elements such as boron, aluminum, silicon, titanium, zirconium, vanadium, manganese,

" cobalt, nickel or their equivalents, may be added to obtain specialproperties 1n the resultant alloy.

All alloys of this type do not forge readily and it is best'to cast the alloys tothe desired shapes of the tools, in carbon or other molds,

and then to finish the articles by a grinding operation. While the properties of hardness and toughness of the alloys may be altered mium and a by heat treatment, these alloys as cast and ground, may be used directly, thus eliminating in general any Heat treatment, and

-merely requiring a grinding operation to furnish the finished tools. This series of alloys are of extreme hardness pete in cutting operations with special alloys such as stellite and the like,- which are, not steel alloys.

Other modes of applying the principle of my invention may be employed instead of the one explained, change being made as re gards the materials employed provided the ingredients stated by any of the following claims or the equivalent of such gredients be employed.

tinctly claim as my invention 1. An alloy steelcontaining carbon, iron, and from 2 per cent to 30 per cent of chroper cent (10% of tungsten or molybdenum 0; both to make the total per cent of chro mium and tungsten or molybdenum or both in excess of 35 per cent.

2. An alloy steel containing carbon, iron, and from 2 per cent to 30 per cent'of chromium and a ercentage, not less than ten per cent (10713, of molybdenum-to make the total per cent of chromium and mplybdenum in excess of 35 per cent.

stated in and com- 1 Itherefore particularly point out and disercentage, not less than'ten 3. An alloy steel containing carbon,iron,

andfrom 2 per cent to 30 per cent of chro-v .mium and a. percentage, not less than ten 1 per cent (10%) of tungsten and molybdenum to make the total per cent of chromium, tungsten and molybdenum in excess of 35 per cent.

Signed by me, this 17th day of October,

' ROY T. 

